Process for the production of quaternary carbon-containing olefins



United States Patent 3,299,159 PROCESS FOR THE PRODUCTION OF QUATER- NARY CARBON-CONTAENING OLEFENS Emmett H. Burlr, .lr., Glenwood, and Byron W. Turnquest, Chicago, 111., assignors to Sinclair Research, Inc., New York, N.Y., a corporation of Delaware N0 Drawing. Filed June 1, 1964, Ser. No. 371,788 a Claims. ((11. 260-677) This invention relates to a process for the production of quaternary carbon-containing olefins.

The quaternary carbon-containing alpha monoolefins have been found to be valuable for the production of polymers of high melting point and polymers possessing other highly desirable characteristics. For example, it has been reported in Linear and Stereoregular Addition Polymers, Gaylord and Mark, Interscience Publishers Inc., New York, 1959, :page 64, that isotactic poly-3,3-dimethyl-lbutene has been produced having a melting point of approximately 300 C. Also a copolymer of ethylene and 3,3-dimethylbutene-1 has been made using a conventional peroxide catalyzed polymerization process which copolymer is characterized by being more flexible and having an increase in extensibility of 300 to 500 percent over low density polyethylene. (See US. Patent No. 2,728,752 to H. C. Brown.)

It is dihicult to manufacture quaternary carbon-containing olefins such as 3,3-dimethylbutene-1. One of the reasons for this problem is the extremely unfavorable equilibrium of these olefins in isomeric mixtures. In the case of 3,3-dimethylbutene-l, for instance, at temperatures of above 127 C, it is the least favored of the C olefin isomers. For example, dehydration of pinacolone alcohol leads to only a 3% yield of 3,3-dimethylbutene-1 which is its equilibrium value in a mixture of dimethylbutenes.-

conventionally, 3,3-dimethylbutene-1 is prepared by a long and involved process which comprises dimerization of acetone by aluminum amalgam to form pinacol, rearranging the pinacol to pinacolone by treatment with an acid catalyst, reducing the pinacolone by catalytic methods to the corresponding alcohol, ile. 3,3-dimethyl- 2-butanol, forming a xanthate or other appropriate ester of the alcohol and subjecting it to thermal pyrolysis to obtain 3,3-dimethy1butene-l. 3,3 -dimethy1butene-l has been obtained by the pyrolysis of the stearic acid ester of 3,3-dimethyl-butanol-2 (see Koch and Van Raay, Brennstoff-Chemie, 32, 161-174, 1951). This process, how ever, causes skeletal re-arrangement to produce in addition, the undesired isomers of the olefin, e.g. 2,3-dimethyll-butene and 2,3-dimethyl-2-butene. The isomer production and the involved procedure of the process thus make it an obviously unpractical method for the commercial production of 3,3-dimethylbutene-l.

Dehydrohalogenation of halogen-hydrocarbons to produce olefins is not new. The production of olefins from halogenated normal paraffins presents no significant problem. In contrast, however, considerable difliculty is experienced in the dehydrohalogenation of halogen-substituted branched chain hydrocarbons, particularly the neocarbon-containing, halogenated aliphatic hydrocarbons of the present invention. These latter structures on dehydrohal-ogenation have a strong tendency to undergo skeletal re-arrangement destroying in large part the neostructure and producing substantial amounts of isomers.

In copending application Serial No. 247,345 to E. H. Burk and Hoffman, filed December 26, 1962, now U.S. Patent No. 3,149,174, incorporated herein by reference, is disclosed a process for the production of high, selective yields of quaternary carbon atom-containing olefins by dehydrohalogenation of the corresponding halogenated 3,299,159 Patented Jan. 17, 1967 hydrocarbons with minimum skeletal isomerization to other olefins of the same carbon atom structure. The process of the copending application comprises dehydrohalogenating a feed material at a temperature of about 403 to 660 C, or even to about 650 C. in a non-catalytic environment. We have now found that even better selective yields of quaternary carbon atom-containing olefins can be obtained for a given conversion level by conducting the non-catalytic dehydrohalogenation in the.

presence of an aromatic hydrocarbon having the formula:

where R is an alkyl radical of up to about 15 carbon atoms, preferably lower alkyl, for instance of 1 to about 4 carbon atoms, especially methyl; :1 is 0 or 1 to 4 or even 6; R is an aromatic hydrocarbon ring, e.g. C H.,; 7 indicates a fused ring relationship (two carbon atoms common to two aromatic nuclei, e.g. as in naphthalene); and m is 0 to 1. When In is 0, n is other than 0. R may also be a divalent alkyl group attached to the aromatic ring at two carbon atoms of the ring, e.g. alkylene, as in tetralin. The preferred aromatics, however, include alkyl benzenes corresponding to the above formula when m is O and n is of the same designation given above. The aromatic rings and R groups may be substituted with other radicals which do not prevent the desired reaction. Suitable aromatic hydrocarbons include toluene, orthoxylene, meta-xylene, para-xylene, ethyl-benzene, ortho ethyltoluene, meta-ethyltoluene, para-ethyltoluene, 1,2,3 trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, alpha-methylnaphthalene, and beta-methylnaphthalene. The total number of carbon atoms in the alkyl side chains can be up to about 20 or 24, and the aromatic is such as to be essentially in the vapor phase under the reaction conditions. The amount of aromatic hydrocarbon employed in the de'hydrohalogenation can vary from about 0.5 to 20 moles of aromatic per mole of the halogen hydrocarbon feed of the invention but is preferably about 2 to 5 moles of aromatic per mole of feed.

The halogenated aliphatic hydrocarbon feed of the present invention maybe represented by the structural formula:

wherein -R is an aliphatic monovalent hydrocarbon radical such as a lower alkyl, including cycloalkyl, of up to 8 carbons, the total carbon atoms in all Rs being up to 18, preferably up to 12. R is a divalent aliphatic hydrocarbon radical of 2 to 8 carbons, preferably 2 to 4 carbon atoms, especially alkylene. R and R may be branched or substituted with non-interfering groups and may be saturated or unsaturated, but are preferably straight chained. X is a halogen atom having an atomic Weight of 35 to 127, preferably the halogen is substituted on a carbon atom beta to the nee-carbon atom. Branched chained paraffins are preferred feedstocks and it is particularly desired that the beta carbon atom be at an end of the carbon chain. Although R and R can be unsaturated, the feed is preferably non-olefinic and non-acetylenic. Suitable feeds include, for instance, l-chloro-3,3- dimethylbutane; 1-chloro-3,3-dimethylpentane;' Z-chloro- 4,4-dimethylpentane, etc.- It is preferred that the feed be monohalogenated. During the reactionHX is lost-to give the corresponding product of one or one additional double bond, preferably in the a-position. Monohalogenated branched chain parafiin react to give the corresponding monoolefins.

In accordance with the present invention the halogenated hydrocarbon feed in vapor form is subjected in the presence of the aromatic to a temperature of about 400 to 600 or even 650 C., preferably 450 to 500 to 575 C. in a non-catalytic environment. Thus, the dehydrohalogenation can be satisfactorily effected in a nonpacked or tubular reactor as long as the reactors internal or contact surfaces are non-catalytic or the dehydrohalogenation may be conducted in such a reactor which contains non-catalytic, particulate contact material. The term particulate is meant to include, in addition to small individual forms such as beads, fragments, shavings, and like particles, other contact forms such as helices, wire meshes, etc. It is important that the contacting surfaces and contacting environment, in addition to being noncatalytic, be essentially free of acidic and basic materials, i.e. be essentially neutral and remain so during the reaction. Similarly, to insure a high selectivity in the dehydrogenation step, metals, metal oxides or other materials that may be present which react with hydrogen halide to give basic or acid environments should be held to a min-imum. Thus the environment is such as to avoid the presence of materials that would cause a significant amount of hydrogen halide ionization. The surface therefore may be non-polar or non-ionic as such or may become so during the initial stages of reaction, which seems to be the case with the high nickel-containing metal surfaces.

Suitable contact surfaces whether they be walls of the reactor or contact materials in particulate form include, for example, quartz, Pyrex glass, ceramic, silica, coke, nickel and nickel alloys containing no more than about 40% iron, preferably less than about 20% or even less than about iron. Included in the metal surfaces suitable for use in the present invention are those containing a high nickel content, usually at least about 40% by Weight and no more than the defined amounts of iron. Preferably the nickel content is at least about 50% or even at least about 75%. Nickel alloys and other nickelcontaining materials having iron or other metals that react with hydrogen halide present in amounts greater than about 40% have been found unsuitable for use in the present invention in that they effect substantial isomerization to isomers of the desired quaternary carboncontaining monoolefins and consequently give a relatively poor selectivity to the desired monoolefins for a given conversion. Metals other than iron that are generally present in nickel alloys in minor amounts do not seem to have a detrimental effect on the selectivity to the desired product of the present invention. Illustrative of a suitable nickel alloy is Hast-Alloy C which is employed in Examples V and XI below. Hast-Alloy C is composed of 50 to 60%, Ni, 4.5 to 7% Fe, and minor amounts of Cr, Wi, Si, Mn, Cu, P and S. Another suitable nickel alloy is Monel metal which is commonly composed of about 68% Ni, 31% Cu and 1% Fe.

When particulate contact materials are employed an LHSV (liquid hourly space velocity) of about 0.5 to 20, preferably about 2 to 10, is generally employed. The reaction can be carried out at atmospheric, subatmospheric or superatmospheric pressure and pressures in the range of about 50 to 150 p.s.i.g. are preferred. If desired an inert gas such as nitrogen or carbon dioxide may be employed in the reaction and the inert gas can be in a ratio of about 0 or 1 to or more moles to 1 mole of hydrogen chloride produced. Under the conditions of the present invention the selectivity to the corresponding quaternary carbon-containing monoolefin is greatly increased and little if any olefins of similar carbon content but without a neo-carbon are found in the crude product.

The feed of the present invention can be prepared by any method known to the art. 1-chloro-3,3-dimethyl 4. butane, for example, can be prepared as described by Louis Schmerling in the Journal of the American Chemical Society, 67, 1152 (1945). Briefly the process involves reacting one mole of ethylene with t-butylchloride using a Friedel-Crafts catalyst such as AlCl FeCl BiCl or ZnCl The reaction can take place at atmospheric pressure when employing the reactive Friedel-Craft catalysts such as AlCl advantageously at a temperature of about 15 C. Under the conditions listed by Schmerling, i.e. complete conversion, the yield of l-chloro-3,3-dime-thylbutane was reported as 75% theory. Fractionation on a simple packed column generally furnishes a chloride of sufficient purity for use in the present invention.

The following examples are included to further illustrate the present invention.

Example 1 A mixture of 3 moles of tetralin (tetrahydronaphthalene) and 1 mole of neohexyl chloride were passed through a 260 cc. Inconel coil at 950 F. and atmospheric pressure. The reaction time in each run was approximately 7 seconds. Inconel is an alloy of Ni, 14% Cr and 6% Fe. The efliuent gas was scrubbed with water, condensed and analyzed. A comparable run was made without tetralin. The results are shown below:

Run A B Tetralin/C Cl (molar) 0 3 Conversion of 0601, percent. 38 38 Wt. Yield, Ultimate percent Cis. G. 4 2. 0 Vinyl Chloride v 2. 8 0. 8 4-methy1pentene-L. 0. 5 0. 2 Neohexene 54. 5 5!). 4 Molar Selectivity to Neoliexene. 78 85. 1

Example 2 A mixture of toluene and neohexyl chloride were passed through the Inconel reactor of Example 1 in the mole ratios indicated below at 950 F., a pressure of 50 p.s.i.g. The reaction time in each run was approximately 30 seconds. The following results were obtained:

Run

Toluene/CnCl (molar) Conversion of C C] Wt. Yield, Ultimate percent Molar Selectivity to Neohexene wherein R is an alkyl radical of up to about 15 carbon atoms; 12 is 0 to 4; R is an aromatic hydrocarbon ring; 1 indicates a fused ring relationship; and m is 0 to l; with the proviso that when m is 0, n is l to 4 and the total number of carbon atoms in the R structure is up to about 20; and in a non-catalytic environment, a halogenated hydrocarbon having the structural formula:

wherein R is an aliphatic monovalent hydrocarbon radical of up to 8 carbon atoms, the total carbon atoms in all Rs being up to 18; R is a divalent aliphatic hydrocarbon radical of 2 to 8 carbon atoms; and X is a halogen atom having an atomic weight of 35 to 127, the mole ratio of said aromatic hydrocarbon to halogenated hydrocarbon being about 0.5 to 20:1.

2. A process for the production of a quaternary carbon-containing monoolefin which consists essentially of thermally and non-catalytically dehydrohalogenating in the vapor form at a temperature of about 400 to 650 C. and in the presence of a lower alkyl benzene a halogenated hydrocarbon having the structural formula:

carbon radical of 2 to 8 carbon atoms; and X is a halogen atom having an atomic Weight of 35 to 127, the mole ratio of the lower alkyl benzene to halogenated hydrocarbon being about 0.5 to 20:1.

3. The process of claim 2 wherein the halogenated hydrocarbon is a 1-halo-3,3-dialkyl branched chain paraffin having a total of up to 12 carbon atoms.

4. The process of claim 3 wherein the halo group is chloro.

5. The process of claim 4 wherein the halogenated hydrocarbon is neohexyl chloride.

6. The process of claim 2 wherein the halogen of the halogenated hydrocarbon is on a carbon atom beta to the neo-carbon atom and the halogenated hydrocarbon contains a total of up to 12 carbon atoms.

7. The process of claim 6 wherein the halogen of the halogenated hydrocarbon is chlorine.

8. The process of claim 5 wherein the mole ratio of lower alkylbenzene to halogenated hydrocarbon is about 2 to 5 :1 and the lower alkyl benzene is a methyl benzene.

9. A process for the production of quaternary carboncontaining monoolefins which consists essentially of thermally dehydrohalogenating in the vapor form at a temperature of about 400 to 650 C. in the presence of an aromatic hydrocarbon having the formula:

wherein R is an alkyl radical of up to about 15 carbon atoms; n is 0 to 4, R is an aromatic hydrocarbon ring; f indicates a fused ring relationship; and m is 0 to 1; with the proviso that when m is 0, n is 1 to 4 and the total number of carbon atoms in the R structure is up to about 20; a halogenated hydrocarbon having the structural formula:

wherein R is an aliphatic monovalent hydrocarbon radical of up to 8 carbon atoms, the total carbon atoms in all Rs being up to 18; R is a divalent aliphatic hydrocarbon radical of 2 to 8 carbon atoms; and X is a halogen atom having an atomic weight of 35 to 127, said dehydrohalogenation being conducted in a non-catalytic environment in contact with a surface containing at least about 40% nickel and a maximum of about 40% iron, the mole ratio of said aromatic hydrocarbon to halogenated hydrocarbon being about 0.5 to 20: 1.

10. The process of claim 9 in which the halogenated hydrocarbon is 1-halo-3,3-dialkyl hydrocarbon having a total of up to 12 carbon atoms.

11. The process of claim 10 wherein the halogen substituent is chlorine.

12. The process of claim 11 in which the halogenated hydrocarbon is 1-chloro-3,3-dimethylbutane.

13. The process of claim 10 wherein the dehydrohalogenation is conducted in a non-catalytic environment and in the presence of a nickel alloy containing up to about 20% iron.

14. The process of claim 9 wherein the mole ratio of aromatic hydrocarbon to halogenated hydrocarbon is about 2 to 5:1 and the aromatic is a methyl benzene.

15. The process of claim 13 wherein the mole ratio of aromatic hydrocarbon to halogenated hydrocarbon is about 2 to 5:1 and the aromatic is a methyl benzene.

References Cited by the Examiner UNITED STATES PATENTS 2,440,497 4/ 1948 Westfield et al. 260-677 ALPHONSO D. SULLIVAN, Primary Examiner. 

1. A PROCESS FOR THE PRODUCTION OF A QUATERNARY CARBON-CONTAINING OLEFIN WHICH CONSISTS ESSENTIALLY OF THERMALLY DEHYDROHALOGENATING IN THE VAPOR FORM AT A TEMPERATURE OF ABOUT 400 TO 650*C. IN THE PRESENCE OF AN AROMATIC HYDROCARBON HAVING THE FORMULA: 